A fundamental problem in biology is to understand how fertilization initiates reproductive development. In higher plants, the ovule generates the female gametophyte which is composed of egg, central, synergid and antipodal cells (Reiser, et al., Plant Cell, 1291-1301 (1993)). All are haploid except the central cell which contains two daughter nuclei that fuse prior to fertilization. One sperm nucleus fertilizes the egg to form the zygote, whereas another sperm nucleus fuses with the diploid central cell nucleus to form the triploid endosperm nucleus (van Went, et al., Embryology of Angiosperms, pp. 273-318 (1984)). The two fertilization products undergo distinct patterns of development. In Arabidopsis, the embryo passes through a series of stages that have been defined morphologically as preglobular, globular, heart, cotyledon and maturation (Goldberg, R. B., et al., Science (1994) 266: 605-614; Mansfield, S. G., et al., Arabidopsis: An Atlas of Morphology and Development, pp. 367-383 (1994)). The primary endosperm nucleus undergoes a series of mitotic divisions to produce nuclei that migrate into the expanding central cell (Mansfield, S. G., et al., Arab Inf Serv 27: 53-64 (1990); Webb, M. C., et al., Planta 184: 187-195 (1991)). Cytokinesis sequesters endosperm cytoplasm and nuclei into discrete cells (Mansfield, S. G., et al., Arab Inf Serv 27: 65-72 (1990)) that produce storage proteins, starch, and lipids which support embryo growth (Lopes, M. A. et al., Plant Cell 5: 1383-1399 (1993)). Fertilization also activates development of the integument cell layers of the ovule that become the seed coat, and induces the ovary to grow and form the fruit, or silique, in Arabidopsis.
Control of the expression of genes that control egg and central cell differentiation, or those that activate reproductive development in response to fertilization is useful in the production of plants with a range of desired traits. These and other advantages are provided by the present application.